The present invention relates generally to systems and methods for providing multisensory treatment for pain reduction and relaxation therapy. More particularly, the present invention relates to a therapeutic system for delivering electrical stimulation to a user in conjunction with audio signal tempo.
Electroanalgesia is a form of pain treatment that relies on the internal or external application of electricity to a user's body. Generally stated, electroanalgesia seeks to prevent pain signals from traveling from the local point of pain origin to the brain. One form of electroanalgesia as is commonly known in the art is transcutaneous electrical nerve stimulation (TENS), the administration of which can treat various forms of pain or otherwise generate relaxing or pleasurable responses in the user in a manner often described as somewhat similar to those which are commonly attributed to acupuncture. It is generally accepted that the human body is favorably responsive to various predetermined and discrete frequencies. Devices using TENS are therefore known to achieve this end by producing pulsating transcutaneous energy to an output electrode system positioned across various portions of the user's body.
Conventional TENS applications use a high stimulation frequency (e.g., 50-150 Hz) and a low intensity current (e.g., 1-2 mA), which is the most tolerable treatment option for the broadest spectrum of users. Other applications are more analogous to acupuncture and may use a low stimulation frequency (e.g., 1-5 Hz) but a high intensity current (e.g., 15-80 mA), which works better for some users than the conventional application but is generally intolerable. An alternative TENS method applies low-intensity stimuli in high-frequency bursts. A variation of TENS methods is transcutaneous acupoint electrical stimulation (TAES), which provides stimulation by alternating high- and low-frequency electrical current in a manner known as dense-disperse.
Another modality is known as percutaneous electrical nerve stimulation (PENS) and inserts exceedingly thin probes into muscle or tissue positioned at internal dermatomal levels rather than using conventional electrodes on the exterior of the body. Such systems therefore bypass skin impedance and provide more direct electrical stimuli.
Yet another electrical stimulation modality known as interferential current therapy (IFC) sums a pair of alternating current signals having a constant intensity but a slightly different frequency to produce a current having a sinusoidal modulation in amplitude at a third (beat) frequency equal to a difference between the frequencies of the pair of signals. When the pair of frequencies are in phase with each other, the current has a relatively high amplitude with respect to conventional TENS applications and a stronger, deeper stimulation may be provided as a result.
IFC modality is an example of burst-modulated alternating current (BMAC) stimulation, as opposed to pulsed current (PC). Another example of BMAC stimulation is Russian current electrical stimulation, which conventionally applies 2.5 kHz alternating current in 50-Hz rectangular bursts of 10 ms duration and with a burst duty cycle of 50%. Recent research in the art has indicated that sensory, motor and pain thresholds may decrease to a plateau with increasing burst duration up to about 10 ms, with no further decrease. However, of burst duration plateaus were found to be different for the various thresholds, meaning that there may be optimal burst durations (e.g., 2-3 ms) where the pain/sensory threshold and pain/motor thresholds are at their maximum and which are dramatically shorter than those typically used in clinical treatment.
User comfort during treatment can vary depending on the pulse intensity and further according to the user him/herself. Intensity is a function of the pulse width and amplitude, where higher pulse intensities are generally less comfortable. In addition users have been found to independently prefer particular pulse frequencies within a given range associated with a particular application. It would be desirable to provide an electrical stimulation system which could therapeutically relax users and alleviate undesirable symptoms across an array of frequencies and below threshold pulse intensities.
Conventional systems and methods for applying electrical stimulation therapy as described herein and as generally known in the art are essentially steady and linear in nature, using a constant current stimulator to inhibit variations in impedance which may otherwise further undesirably result in increased current intensity. It would further be desirable and potentially more therapeutic to provide a delivery method originating from a more organic source such as rhythm or music and yet still inhibiting the increases in current intensity.